[Show abstract][Hide abstract] ABSTRACT: Cyclin G1 is the only cyclin that has either positive or negative effects on cell growth. Our previous study found decreased expression of cyclin G1 in human endometrial carcinoma tissues compared with normal endometrial tissues. The study aimed to evaluate cyclin G1 expression and its effect on proliferation of human endometrial carcnimoa cells (ECCs). Cyclin G1-GFP (green fluorescence protein) plasmid was constructed and transfected into various differentiated human ECCs, including Ishikawa, HEC-1-B and KLE cells, and proliferation of the transfected cells was determined by the CCK- 8 method. Exogenous cyclin G1 mRNA and protein were measured by RT-PCR and western blot, respectively, and GFP signal was monitored by fluorescence microscopy. Chinese hamster ovary (CHO) cells were transfected with the same constructs as a cell control. Cyclin G1-GFP- transfected Ishikawa cells were further treated with MG132, an inhibitor of proteasome, to analyze if low expression of cyclin G1 is related to its abnormal degradation in ECCs. Ectopic expression of exogenous cyclin G1 was found to significantly suppress the proliferation of Ishikawa and HEC-1-B cells but not KLE cells. Compared with cyclin G1-transfected CHO cells, exogenous cyclin G1 protein expression was low in Ishikawa and HEC-1-B cells, and was undetectable in KLE cells. However, all ECC lines and CHO cells expressed similar levels of exogenous cyclin G1 and GFP mRNA. MG132 treatment increased cyclin G1 protein expression in cyclin G1-GFP-transfected Ishikawa cells. This is the first study to present evidence to suggest that cyclin G1 exerts negative control on proliferation of ECCs. Exogenous cyclin G1 shows different protein expression levels in ECCs with different malignancies, and cyclin G1 protein is highly unstable and is rapidly degraded in ECCs.
No preview · Article · Apr 2013 · The Chinese journal of physiology
[Show abstract][Hide abstract] ABSTRACT: Cyclin G1 protein is expressed in normal endometrial epithelial cells in a progesterone-dependent manner. It is an important mediator of the inhibiting effect of progesterone on cell proliferation. Moreover, the expression of cyclin G1 is also found to be decreased in human endometrial carcinoma cells (ECCs). To study the mechanism of decrease in the expression levels of cyclin G1, 3 ECC cell lines, Ishikawa, HEC-1-B, and KLE cells were treated with progesterone (P(4)). The KLE cells, in which progesterone receptor (PR) expression was absent, were transfected with PR-expressing plasmid before treatment with P(4). The results showed that cyclin G1 expression increased in Ishikawa and HEC-1-B cells after treatment with P(4), additionally the cell proliferation was suppressed but not in KLE cells. When the PR-expressing plasmid was transfected into KLE cells, the effect of P(4) was restored. Our data suggest that the deficiency of progesterone and its receptors is an important cause of the decreased expression of cyclin G1 in endometrial carcinoma, which may account for carcinogenesis and development of endometrial carcinomas.
No preview · Article · May 2012 · Reproductive sciences (Thousand Oaks, Calif.)
[Show abstract][Hide abstract] ABSTRACT: To study whether integrins on cell membrane ligate with intracellular cytoskeletal proteins and mediate their reorganization in egg activation, female mice were used for superovulation. The zona-free oocytes were incubated separately with specific ligand of integrins, an active RGD peptide, in vitro for certain period of time. RGE peptide and mouse capacitated sperm were used as controls. Freshly ovulated oocytes and those treated with different factors were immunostained with FITC-labeled anti-actin antibody, then detected with confocal microscope. The results demonstrated that freshly ovulated mouse oocytes, oocytes incubated for 2 h in vitro and those treated with control RGE peptide for 15 min showed hardly visible fluorescene or only thin fluorescence in plasma membrane region. Oocytes coincubated with sperms for 15 min and those treated with active RGD peptide for 10 min, 30 min and 2 hours respectively had strong and thick fluorescence in the plasma membrane and cortical region of oocytes, and some of them showed asymmetrically fluorescent distribution. It is proved that integrins on membrane are ligated directly with cytoskeletal protein. Integrins binding with their ligands regulate reorganization of cytoskelal protein, which may be involved in transmembrane signaling in egg activation.
No preview · Article · Jan 2005 · Science in China Series C Life Sciences
[Show abstract][Hide abstract] ABSTRACT: This study was aimed to disclose whether the VLA-5 integrin on human sperm membrane takes part in the activation of human spermatozoa.
Fluo-3/AM was coincubated with human spermatozoa. The change of intracellular calcium([Ca2+]i) was determined by flow cytometry when human sperms were exposed to Fibronectin(Fn) as the specific ligand of integrin VLA-5. Human sperm acrosome reaction(AR) rate was evaluated by triple-stain technique.
Fn significantly raised the AR rate (P < 0.05) and the level of [Ca2+]i (P < 0.01) in the spermatozoa of fertile men. But there was no significant rise in the level of [Ca2+]i in the spermatozoa of infertile men.
The VLA-5 integrin on human sperm membrane plays a role in the activation of sperm.
No preview · Article · Jul 2003 · Sichuan da xue xue bao. Yi xue ban = Journal of Sichuan University. Medical science edition